1. Field of the Invention
This invention relates to systems employing desiccants to extract unwanted moisture, alone or mixed as a contaminant with the contents, in tanks and large enclosed spaces. More particularly, the invention relates to such systems as are employed to remove condensed, entrained, or emulsified water from reservoirs of hydrocarbonaceous fluids. Such reservoirs might typically include vehicle fuel tanks and fuel or oil storage tanks above or below the ground.
2. Background Art
The infiltration of moisture into the contents of large storage containers presents a problem in many areas. In grain storage silos, for example, the presence of excessive moisture in the contents can have ruinous consequences. Often, such moisture results from leakage into the silo or from condensation therewithin.
Water infiltration into and the resultant contamination of hydrocarbon fluids due to condensation, hydroscopic attraction, and poor container closures is also a problem of substantial concern with regard to hydrocarbon fuels and oils. Tank and delivery systems that must utilize contaminated fuels suffer from problems such as icing, rust, and algae growth caused by water. Additionally, water causes damage to close-tolerance devices, such as fuel injector pumps and injection nozzles that rely for lubrication upon the passage of fuel that is contaminated by water.
A number of chemical solutions to water infiltration have been devised. Alcohol, for example, allows water to solubilize in a hydrocarbon and thus acts as an antifreeze. Nevertheless, alcohol can cause even greater damage to close-tolerance devices than does water because of its solvent action. Recently, some non-alcohol based additives have been devised toward this same end, but both types of additives must be added to the products with which they are used at an arbitrary ratio due to the inability to make an accurate prediction as to how much water will eventually become present in the oil or fuel involved. Where the conditions of storage or manner of handling lead to excessive water contamination, such additive-treated hydrocarbon products may thus be deceptively assumed to not pose the risks mentioned above from water contamination.
In larger storage tanks for fuel and oil, infiltrating water will frequently accumulate in a pool at the bottom of the container, below the hydrocarbon product. Sophisticated devices are available that measure the amount of water in such pools. These devices alert an operator when a predetermined water level is reached, so that the water can be drained, if by good fortune the tank has been so designed and constructed. Nevertheless, such devices are far from economical in smaller storage tanks, such as the fuel tanks on trucks, airplanes, and certain recreational vehicles, such as snowmobiles. The tanks on these vehicles are often subjected to extreme temperature conditions and changes, which exacerbate the condensation of moisture and its potential for assuming a solid state.
As an alternate method of removing the water from such enclosures and the contents therein, water-specific absorbent materials, such as desiccants, have been employed. In one instance, a soaking device comprising such a desiccant and a ballast for settling the device in a hydrocarbonaceous fluid are secured within a tethered pouch and lowered into the tank from which water is to be removed. The use of specific types of fabric in the pouch and reusable desiccants can permit water to be mechanically wrung out of the pouch so that it may be employed repeatedly. Such devices are, however, vulnerable to rupture from protrusions on the interior of such tanks, and the weight of the ballast within the pouch can be a source of mechanical strain on the fabric thereof, also leading to rupture of the pouch. The subsequent release of desiccant and ballast is frequently a more damaging contamination than the water the apparatus was designed to remove.
As mentioned previously, water in storage containers of gasoline and oil will seek the lowest point in the storage container and accumulate there. Unfortunately, desiccant containers of the type described above are most often soft, bag-like structures so designed to accommodate the expansion of the desiccant therein as moisture is absorbed. These desiccant containers by lacking rigidity, tend to remain on the floor of the storage container where they first land. Unless the container floors involved are sufficiently steep, these flacid bag-like structures cannot be induced to seeking the lowest point in the container where unwanted water is most likely to be accumulated. As a result inadequate or unacceptably slow extraction of water is effected.